A windscreen that looks clean in the morning can be almost impossible to see through at four o'clock on a December afternoon. Low sun hits the glass and every smear, fingerprint and patch of greasy film on the inside lights up at once. Add a bit of misting and you are driving through a white haze.
Knowing how to clean windscreen glass properly fixes most of that. The outside is easy. The inside is where people get streaks, because the film there is greasy and the angle is awkward. This is the method we use on our own cars.
The short version: clean the outside first, then the inside. Spray Ballistol Glass Cleaner onto a microfibre cloth, not onto the glass, and wipe in overlapping strokes. Buff dry straight away with a second clean cloth before the cleaner dries. Do the inside in vertical strokes and the outside in horizontal ones, so you can tell which side any streak is on.
Why the inside of a windscreen gets so grubby
Most of the film on the inside comes from the car itself. Dashboard plastics and trim give off vapours, more so when the sun heats the cabin, and those settle on the coldest surface, which is the glass. Breath, dust from the heater, and smoke or e-cigarette vapour all add to it. Hands are the other cause: every time someone pushes the windscreen to adjust a sat nav or wipes away mist with a glove, they leave grease behind.
That is why wiping a misted screen with your sleeve makes it worse. It spreads the grease into a smeared layer that scatters oncoming headlights.
What you'll need
- Ballistol Glass Cleaner. It uses surfactants to lift fingerprints, grease, nicotine, soot, dust and vape residue, and it leaves an invisible film that slows the dirt coming back
- Two or three clean microfibre cloths, ideally short-pile or waffle weave, kept only for glass
- A bucket of warm water and a sponge for the outside
- Optional: Ballistol Universal & Plastic Cleaner for the dashboard top
Wash glass cloths without fabric softener. Softener coats the fibres and that coating ends up on the windscreen as streaks you can't buff out.
How to clean windscreen glass on the inside
Park in the shade and let the glass cool if the car has been in the sun. Cleaner dries too fast on hot glass and leaves marks. Turn the engine off and open a door or two for some air.
- Wipe the dashboard top first if it's dusty. Otherwise the dust ends up on your cloth and back on the glass. A light spray of Universal & Plastic Cleaner on a cloth does it, and the treated plastic stays dust-repellent for a while afterwards.
- Dry-wipe the inside of the windscreen with a clean microfibre cloth to take off loose dust.
- Spray two or three bursts of Glass Cleaner onto a folded cloth. Spraying at the glass sends overspray onto the dashboard and down onto the air vents and any electronics under the screen.
- Clean one half of the windscreen at a time. Sit in the passenger seat to do the driver's side, which gives you a better reach into the bottom corner where the glass meets the dash.
- Wipe in overlapping vertical strokes, top to bottom, pressing firmly. Fold the back of your hand against the cloth to get right into the lower edge.
- Buff the area dry with a second clean cloth straight away, before the cleaner has a chance to dry on.
- Look through the glass from the driver's seat, then from outside with the light behind it. Re-do any patches that still show smears.
- Do the side windows, mirrors and rear screen the same way. On a heated rear screen, wipe along the elements, not across them.
A badly filmed windscreen often needs two passes. The first lifts the grease, the second leaves it clear. If you still see a haze in low sun after that, the cloth is usually the problem. Swap to a fresh one.
Cleaning the outside and the wipers
If you're washing the car, do the glass last so you aren't washing car shampoo and wax residue back onto it. Otherwise rinse the windscreen with warm water and a sponge to get grit off before you wipe it. Rubbing dry grit across the glass is how people scratch it.
Squashed flies and tree sap are the stubborn bits. Spray Glass Cleaner straight on, give it a minute to soften the residue, then wipe and buff. Use horizontal strokes on the outside. Then if you spot a streak when you are back in the driver's seat, you know which side it's on.
Lift each wiper and wipe the rubber blade with a damp cloth until the cloth comes away clean. A dirty blade drags a grey arc across clean glass at the first swipe. If the blades still smear after cleaning, the rubber is worn or split and they need replacing.
Keep oily sprays, polish and tyre dressing off the glass. Even a fine mist of oil drifting across from a job on the door hinges will make the wipers judder and smear. If that happens, clean the glass and the blades again until the water sheets off evenly.
How often to do it
| Job | Winter | Rest of the year |
|---|---|---|
| Inside of windscreen | Every 2 to 3 weeks | Monthly |
| Outside of windscreen | Weekly, or whenever road spray builds up | Every wash, plus fly removal in summer |
| Wiper blades | Every 2 weeks | Monthly |
| Side windows and mirrors | Monthly | Monthly |
Cars that are smoked or vaped in, or that carry dogs, need the inside done more often. You will see it in the low sun before anything else.
Clear glass and the law in the UK
This is a safety job as well as a cosmetic one. The Highway Code says you must be able to see out of every window before you set off in winter, which means clearing ice, snow and mist from all of them, not just a porthole in the windscreen. The rule is set out in the Highway Code guidance on driving in adverse weather. A filmed screen mists faster and takes longer to clear.
Keep the washer bottle topped up with a screenwash rated for freezing temperatures. Plain water freezes in the jets and the reservoir.
Common mistakes
Cleaning in full sun is the most common one. The cleaner flashes off before you can buff it and leaves a pattern of streaks. Kitchen roll is another, as it leaves lint in the corners.
Don't scrape the inside of a heated rear screen or tinted glass with anything harder than a cloth. The heating elements and tint film are easy to damage and expensive to put right. If your car has aftermarket tint, ask the fitter which cleaners they recommend.
Keep cleaning products out of children's reach and away from your eyes. The safety data sheets for the whole range are on our technical data page.
Questions people ask
What is the best way to clean the inside of a windscreen? Spray glass cleaner onto a microfibre cloth rather than the glass, wipe the windscreen in overlapping vertical strokes, then buff it with a second dry cloth before it dries. Sitting in the passenger seat makes the driver's side corner much easier to reach.
How do you clean car windows without streaks? Use two clean microfibre cloths, one to clean and one to buff dry, and don't let the cleaner dry on the glass. Work in the shade on cool glass, use a small amount of cleaner, and wash your cloths without fabric softener, which leaves a film.
What is the best cloth to clean car windows? A short-pile or waffle-weave microfibre cloth works best on glass because it holds the dirt and leaves no lint. Keep separate cloths for glass so they never pick up polish, wax or oil from the bodywork.
Why does the inside of my windscreen get so dirty? Plastics in the dashboard give off vapours that settle on the glass, especially when the sun heats the car. Breath, heater dust, smoking and vaping add to it, and the film shows up as glare and smearing when the sun is low or the glass mists.
Can you use household glass cleaner on car windows? On plain glass, a good glass cleaner works. If your car has aftermarket window tint, check with the fitter before using any cleaner containing ammonia, and never use a blade or scourer on tinted or heated rear glass.
Ballistol Glass Cleaner works on windscreens, windows and mirrors, and the rest of the Automotive range covers the dashboard, wheels and waterless cleaning. For advice on a particular job, call +44 (0) 7817 267314 or email sales@ballistol.co.uk. Our car and motorbike care page has the winter jobs for the rest of the car.
More guides: How to Stop Rust on Metal · How to Clean a Bike Chain
